I will discuss our recent discovery of imprints on the cosmic
microwave background from the most extreme voids and clusters in the SDSS
Luminous Red Galaxy (LRG) survey. These imprints are consistent with the
Integrated Sachs-Wolfe (ISW) effect, a signature of dark energy, and
constitute the highest-significance detection of the ISW from a single
dataset. Also, I will discuss our efforts at detecting the ISW effect
using the gravitational potential generated from the LRG's.